Materials such as polyvinyl chloride (PVC) artificial leather, polyurethane (PU) artificial leather, natural leather, textiles, and the like may be processed and used as an interior sheet for vehicles. In order to impart final surface physical properties to these materials, polyvinyl chloride artificial leather, polyurethane artificial leather, and natural leather are generally surface-treated with a heat curable treating agent. The sheets obtained by surface treatment with heat curable treating agents have limitations in accomplishing required surface physical properties such as stain resistance for jeans and the like.